The sophistication and uses of electrical devices have increased dramatically. Consumer items having electrical components are ubiquitous in communications, computing, entertainment, transportation, etc. Numerous people rely upon or have grown accustomed to usage of electrical devices for business, education, or for other needs. Electronic devices are increasingly portable to accommodate these needs during travels from home or the workplace. The sophistication and capabilities of power supplies for such devices have also improved to meet the requirements of the electronic consumer devices. For example, cost, size, and capacity are some product characteristics which have been improved for the portable power supplies. In addition, portable power supplies are being used in additional applications. For example, there is increased interest upon usage of alternative energy sources including electrical energy for an expanding number of applications, such as transportation applications.
Exemplary portable power supplies such as batteries store electrical energy. It may be beneficial to know the state of charge of the batteries during operation of the electrical devices. However, challenges are presented with respect to determining state of charge information with respect to some battery cell chemistries. In one example, it may be difficult to monitor battery cells which have a substantially flat discharge profile.
At least some aspects of the disclosure provide methods and apparatus for monitoring charge of batteries.